Since non-volatile semiconductor memory devices are excellent in portability and impact resistance, their demand has been extended rapidly in recent years as memory devices for small-size portable information equipments such as portable personal computers or digital steal cameras. For growing the market, increase in the memory density by decreasing of the memory cell area is an important factor and various memory cell systems have been proposed therefor.
Japanese Unexamined Patent Application Publication No. 2004-272975 discloses a resistance change memory device in which multiple memory cells are connected in series in a lateral direction. As shown in FIG. 1 of Japanese Unexamined Patent Application Publication No. 2004-272975, each of the plurality of memory cells has a structure in which a transistor as a selection element and a variable resistance element as a memory element are connected in parallel. As shown in FIG. 5(b) of Japanese Unexamined Patent Application Publication No. 2004-272975, transistors are formed above a substrate and variable resistance elements are formed thereabove. Further, contacts are formed each between the transistor and the variable resistance element for electric connection. Since each of the contacts is used in common between each of adjacent transistors, the number of contacts per cell is decreased and, as a result, the memory cell area is also decreased.
Japanese Unexamined Patent Application Publication No. 2008-160004 discloses a resistance change memory device in which multiple memory cells are connected in series in a vertical direction. The memory cell of Japanese Unexamined Patent Application Publication No. 2008-160004 has a structure in which a transistor as a selection element and a phase change device as a memory elements are connected in parallel in the same manner as Japanese Unexamined Patent Application Publication No. 2004-272975 and a gate insulating film, channel silicon and a phase change element are buried in a hole passing through a structure where gates and insulating films are stacked alternately.